Nearly Complete Skull of a Dome-Headed Dinosaur Makes Its Way to the Smithsonian’s National Museum of Natural History

Millions of years ago, an odd-looking dinosaur roamed what’s now North America. The unusual creature walked on two legs, used a beak to munch on plants and had a domed head surrounded by knobby horns—which it possibly used to butt heads with other animals.

Now, a remarkably well-preserved skull of this dinosaur, called Pachycephalosaurus, or “thick-headed lizard” in Greek, has joined the fossil collection at the Smithsonian’s National Museum of Natural History (NMNH). Visitors can view the specimen from December 22 through December 28 in the museum’s FossiLab—a working fossil preparation laboratory—before it gets whisked off so researchers can learn about the animal’s life 67 million years ago.

“This skull is by far the most spectacular specimen of this type of dinosaur that we have at the museum,” says Matthew Carrano, a paleontologist and NMNH’s curator of Dinosauria, in a press release. “We almost never get to see the animal’s face or the teeth or other parts of the head because they usually have broken away.”

After at least one or two years of scientific investigations, the skull will join NMNH’s permanent display in the Hall of Fossils, reports the Washington Post’s Michael Laris. The museum also plans to create a digital 3D version of the specimen that will allow researchers around the world to conduct their own analyses of it.

Pachycephalosaurus dinosaurs are estimated to have weighed around 1,000 pounds and reached up to 15 feet long, making them medium-sized dinosaurs. Their odd heads make them popular subjects of books and documentaries, and they’re often depicted ramming their thick skulls into rivals.

But researchers aren’t sure that was the purpose of their round, spikey noggins, Carrano says in the press release. The lives of these dinosaurs and their kin have remained mysterious, largely because only fragments of their fossilized remains are generally recovered. Most specimens primarily consist of the animals’ head domes.

Pachycephalosaurus bones are also hard to come by. Remains of this type of dinosaur account for less than one percent of fossils unearthed at the famous bonebed where the skull was discovered.

For a researcher, the “dream is to walk along the Badlands and see a skull staring out of the ground at you. And it hardly ever happens,” Kirk Johnson, a paleontologist and director of NMNH, tells the Post. “It happened this time.”

A private dinosaur hunter noticed an eye socket popping out of the ground in the South Dakota portion of the Hell Creek Formation, according to the outlet. This rock layer holds remnants of the last 1.5 million years of the Cretaceous period, which ended when an asteroid struck Earth 66 million years ago, killing all non-avian dinosaurs.

The skull was recovered in 2024, and philanthropists Eric and Wendy Schmidt purchased it earlier this year at a Sotheby’s auction, after which they gifted it to NMNH. It’s one of few known Pachycephalosaurus skulls that are nearly complete. This specimen contains 32 different cranial bones, several teeth and even replacement teeth growing in its jaws. Studying the bones should help paleontologists pinpoint standalone Pachycephalosaurus teeth in the Hell Creek Formation.

Additionally, Carrano plans to take CT scans of the skull, which will allow a peek into internal structures, such as the dinosaur’s brain cavity. “We can understand the shape and size of the brain and the position of each individual bone, which is really difficult to do when the outside looks basically like a bowling ball,” he says in the press release.

No evidence points to the Pachycephalosaurus’s thick skull “protecting some bit of genius,” Carrano tells the Post, but perhaps his upcoming research on the specimen will shed some light on the ancient creature’s intelligence level, which currently is “a total mystery.”